There are a variety of sensing devices on the market that are capable of providing an indication of stimuli. Many incorporate electrical elements that are subjected to some form of manipulation caused by the physical quantity being sensed, thereby causing a change in their electrical characteristics. One example of such sensing devices is a MEMS (“Micro-Electro-Mechanical Systems”) pressure sensor. A typical such MEMS pressure sensor includes a small, thin silicon chip or diaphragm onto which a number of resistances that function as strain gauges (for example, piezoresistors) are formed by well-known processes in a Wheatstone bridge. In operation, stresses caused by pressure applied to the chip or diaphragm change the resistance values of the piezoresistors in the Wheatstone bridge (the applied pressure causes the chip or diaphragm to deflect, which deflection creates compressive and tensile forces in the resistances thereby causing a change in their electrical values). An electronic circuit detects the changes in resistance values, and outputs an electrical signal representative of the applied pressure.
Differential pressure sensors are used to measure pressure differences between two pressure sources. It is known to use separate Wheatstone bridge arrangements of interconnected resistances as pressure sensors for measuring each of the two pressure sources. Ideally, in order to provide an accurate differential pressure measurement, the output voltage versus pressure characteristics for each of the bridge pressure sensors should be similar and should remain similar despite factors such as changing temperature.
The above described pressure sensors are sensitive to various disturbances, such as temperature changes, which, if uncompensated, will cause errors in the pressure reading. Temperature induced errors may be observed, for example, as a change in the output of the sensor as temperature varies with zero pressure applied, and as a change in the difference between the full-scale output and the zero pressure output as the temperature varies with full-scale pressure applied.